How to work around SOAP request protocol error with VMware-vSphere-Perl-SDK-5.5.0

During a move from vSphere 5.0 to 5.5 I ran into errors using the Perl scripts provided with the VMware vSphere Perl SDK for 5.5 on Fedora 20. The symptom was the following response to calling vminfo.pl:

The recommended solution was to use an older version of libwww-perl, in particular 5.837. But many of the packages on my system depend on libwww-perl and I didn’t want to mess with such a critical piece of my environment. The solution was to download the older version of libwww-perl, install it into a non-system location and to set the environment variable PERL5LIB to point to the new location before calling the vSphere Perl SDK scripts.